
function getLiveCodeOptions() {
var START = `
import sketch
code = open("main.py").read()
env = dict(sketch.__dict__)
exec(code, env)
`

var SKETCH = `
import json

def sendmsg(msgtype, function, args):
  """Sends a message to the frontend.

  The frontend will receive the specified message whenever
  this function is called. The frontend can decide to some
  action on each of these messages.
  """
  msg = dict(msgtype=msgtype, function=function, args=args)
  print("--MSG--", json.dumps(msg))

def _draw(func, **kwargs):
  sendmsg(msgtype="draw", function=func, args=kwargs)

def circle(x, y, d):
    """Draws a circle of diameter d with center (x, y).
    """
    _draw("circle", x=x, y=y, d=d)

def line(x1, y1, x2, y2):
    """Draws a line from point (x1, y1) to point (x2, y2).
    """
    _draw("line", x1=x1, y1=y1, x2=x2, y2=y2)

def rect(x, y, w, h):
    """Draws a rectangle on the canvas.

    Parameters
    ----------
    x: x coordinate of the top-left corner of the rectangle
    y: y coordinate of the top-left corner of the rectangle
    w: width of the rectangle
    h: height of the rectangle
    """
    _draw("rect", x=x, y=y, w=w, h=h)

def clear():
    _draw("clear")

# clear the canvas on start
clear()
`
  const CANVAS_FUNCTIONS = {
    circle: function(ctx, args) {
      ctx.beginPath();
      ctx.arc(args.x, args.y, args.d/2, 0, 2*Math.PI);
      ctx.stroke();
    },
    line: function(ctx, args) {
      ctx.beginPath();
      ctx.moveTo(args.x1, args.y1);
      ctx.lineTo(args.x2, args.y2);
      ctx.stroke();
    },
    rect: function(ctx, args) {
      ctx.beginPath();
      ctx.rect(args.x, args.y, args.w, args.h);
      ctx.stroke();
    },
    clear: function(ctx, args) {
      var width = 300;
      var height = 300;
      ctx.clearRect(0, 0, width, height);
    }
  }

  function drawOnCanvas(canvasElement, funcName, args) {
    var ctx = canvasElement.getContext('2d');
    var func = CANVAS_FUNCTIONS[funcName];

    var scalex = canvasElement.width/300;
    var scaley = canvasElement.height/300;

    ctx.save();
    ctx.scale(scalex, scaley);
    func(ctx, args);
    ctx.restore();
  }

  return {
    runtime: "python",
    files: [
        {filename: "start.py", contents: START},
        {filename: "sketch.py", contents: SKETCH},
    ],
    command: ["python", "start.py"],
    codemirror: true,
    onMessage: {
      draw: function(editor, msg) {
        const canvasElement = editor.parent.querySelector("canvas");
        drawOnCanvas(canvasElement, msg.function, msg.args);
      }
    }
  }
}
